The Malaysian police Thursday arrested a lawyer of a local politician who has been urging the United States to investigate the corruption scandal involving Prime Minister Najib Razak. The lawyer, identified by Reuters as Matthias Chang, was visiting Khairuddin Abu Hassan, a former member of the country’s ruling party who was also arrested last month.

“Matthias and I visited Mr. Khairuddin this afternoon at 2 p.m. for about 30 minutes,” lawyer Mohd Akmal Afiq Mohd told the Wall Street Journal. “When we came out, police informed Matthias he was being arrested.”

Both Khairuddin and Chang are being held under the country's Security Offenses (Special Measures) Act, which would allow them to be detained for 28 days, the Journal report added.

It was not immediately clear what charges would be filed against Chang, a police spokeswoman told Reuters.

Chang is an associate of former prime minister Mahathir Mohamad, who is now heading a campaign calling for Najib to step down from his post over the bribery allegations. Also on Thursday, the country’s attorney general defended the government and said it had studied the central bank's investigation report into state investor 1Malaysia Development Bhd (1MDB) and found no wrongdoing by the fund officials, the Associated Press reported.

Khairuddin was ousted from Najib’s United Malays National Organisation in February after he was declared bankrupt. Following this, he traveled to several countries, campaigning against Najib and 1MDB, before his arrest last month.

Khairuddin was detained at the Malaysia airport on Sept. 18 when he was about to board a flight to the U.S. to persuade Washington to investigate. He reportedly alleged that American banks were also involved in the scandal. He was arrested on charges of undertaking activities detrimental to parliamentary democracy, according to Reuters. Chang was also planning to travel with Khairuddin to the U.S., the Journal reported.

The financial scandal unfurled in July when a Wall Street Journal report said that investigators were probing 1MDB over transfer of nearly $700 million into Najib’s personal accounts. Najib, who has faced several anti-government protests, has denied the accusations, saying that the money was a donation from the Middle East. The fund 1MDB, which was founded by Najib in 2009 with an aim to develop new industries, also has been accused of mismanagement after it gathered a debt of nearly $10 billion.